[Physics] Why must the wavelength of light be smaller than uncertainty in position

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I have read that to measure the position of a particle to an accuracy $\Delta x$, we need light of wavelength $\lambda < \Delta x$. Is it true? Why is it so?

Best Answer

It is because the wavelength is being used as a yardstick to measure the object ( actually the uncertainty in its position). You can measure a 10 meter object with a meter stick, but you can't measure a 10 cm object with the meter stick (assuming no markings on the stick)